Fuel cells typically include a membrane such as a polymer electrolyte membrane (PEM), which conducts protons and is sandwiched between a cathode catalyst layer and an anode catalyst layer. Gas diffusion medium (GDM) layers may engage the cathode catalyst layer and the anode catalyst layer, respectively. In some applications, the catalyst layers are coated on the GDM, whereas in other applications, the catalyst layers are coated on the membrane. The membrane, two catalyst layers and two GDM taken collectively are referred hereafter as the Membrane Electrode Assembly (MEA). Disposed outside of the MEA are conductive separator (bipolar) plates for mechanically securing the MEA and electrically connecting adjacent MEAs in series. A portion of each separator plate which is disposed in contact with the MEA is provided with a gas passage for supplying either a fuel such as hydrogen gas or an oxidant such as oxygen gas to the respective electrode surface and for removing generated water. A coolant may also flow through the bipolar plate.
In order to prevent leakage of the hydrogen fuel gas supplied to the anode and oxygen gas supplied to the cathode and prevent mixing of the gases in the fuel cell, heretofore, a gasket is arranged on the periphery of each electrode catalyst layer, with the membrane sandwiched there between. During assembly of the fuel cell, the bipolar plates make contact with the compressible gasket material, thus producing the barrier to gas leakage.
In fuel cells, premature MEA failure has been observed at the catalyst layer edges of MEAs. To protect the catalyst layer edges from premature failure, gasket edge protection materials have been introduced into the MEA architecture. The edge protection materials are either situated between the membrane and each of the respective catalyst layers or between each of the catalyst layers and the respective GDM. The edge protection materials typically cover the membrane outside of the catalyst layer edge. Often, the edge protection materials extend over the inside edge of the catalyst layer edges. However, premature failures were still found in the region of the catalyst edge underneath the edge protection materials.